Effect of endomycorrhizae on the bioavailability of bound 14C residues to onion plants from an organic soil treated with [14C]fonofos

Uptake of bound 14C residues from an organic soil treated with radiolabeled fonofos (O-ethyl S-phenyl ethylphosphonodithioate) by selected Glomus endomycorrhiza and onion roots was studied. The hyphae of endomycorrhizal associations were capable of removing 14C residues from the soil and transporting them to onion plants. Bioavailability of soil-bound 14C residues, as measured by 14C residue content in onion, was increased 32 and 40% over that of nonmycorrhizal plants by hyphae of Glomus intraradices and Glomus vesiculiferium, respectively. The data suggest that under field conditions endomycorrhizal infection may greatly increase the bioavailability of soil-bound pesticide residues to plants